The invention relates to an electrical connector and more specifically to one that can be locked onto a male electrical plug.
Extension cords have been used for may years to lengthen the cord of an electrical device so that it can reach a remote power supply or receptacle. One end of the extension cord has a female socket that is sized to engage with a plug located on the cord of the electrical device while the other end of the extension cord is formed with a plug which is adapted to engage with a socket located at the power supply.
Quite often, when the user is moving the electrical device the cord or the extension cord becomes entangled or caught, the extension cord becomes disconnected from the cord of the device or the power supply. When this occurs, the user is forced to discontinue operation and reestablish the electrical connection, thereby adding time to complete the task. Another problem is that when the extension cord partially disconnects from the power source, it has hot electrical contacts exposed to the user and the environment. In this situation, a person could accidently touch the electrical contacts and sustain injury or the electrical contact may short and cause a fire and/or damage to the device, power supply or user.
In order to prevent the extension cord from becoming disconnected from the electrical device, users have often resorted to means such as tying a knot in the cord of the device and the socket end of the extension cord to isolate the plug/socket connection from the induced stress. This method, is time consuming and can damage the insulation surrounding the conductor, and shortens the effective life of the cord.
To overcome the above disadvantages, extension cords have been designed with a variety of locking mechanisms to securely connect the extension cord to the device or power supply. One such extension cord is shown in U.S. Pat. No. 4,085,991. It utilizes structure allowing for engagement of the apertures formed in the prongs of a male electrical plug. Once engaged, the two members cannot be pulled apart and there is structure for releasing that engagement. A similar method of locking a connector onto the male prong of a male electrical plug is illustrated in U.S. Pat. No. 5,352,132.
Other prior art patents of interest are the following. The Chesler U.S. Pat. No. 3,691,327 discloses a circuit-closing adaptor having a key-operated lock means that closes the electrical circuit when the key is in the lock and which opens the circuit when the key is removed from the lock.
The Sherman U.S. Pat. No. 4,167,658 is directed to an electrical lock having a housing carrying a pair of prongs to be mounted in a conventional wall socket. It has a key operated cam in the housing that makes and breaks one of the contacts and latching means carried by that contact that mechanically locks onto the plug prong. The Solomon U.S. Pat. No. 4,579,410 is directed to a security attachment for an electrical plug that is effective to prevent unauthorized use and to readily permit authorized use.
The Windsor Jr. U.S. Pat. No. 4,875,874 is directed to a rotatable electrical connector arrangement for the secure snag free interlocking of the female end socket member of an electrical power extension cord, to the plug or male end member of an electrical power implement, or to any related device having a male plug member fixed to its power cord. The Torok U.S. Pat. No. 5,108,301 is directed to a locking electrical cord connector that securely attaches at both the male and female end.
It is an object of the invention to provide a novel lockable electrical receptacle that can be installed on the female end of an electrical cord or an extension cord.
It is also an object of the invention to provide a novel lockable electrical receptacle that will prevent accidental disconnection.
It is another object of the invention to provide a novel lockable electrical receptacle that will prevent downtime previously caused by the electrical connections pulling apart.
It is an additional object of the invention to provide a novel lockable electrical receptacle that will reduce the cost of labor caused by downtime delays.
It is a further object of the invention to provide a novel lockable electrical receptacle that is easy and fast to install.
It is also an object of the invention to provide a novel lockable electrical connector that is inexpensive to manufacture and market.
The first embodiment of the lockable electrical receptacle has a cylindrical housing with a pair of laterally spaced electrical prong apertures and a ground pin aperture formed in its front wall. A left blade prong terminal and a right blade prong terminal and a ground pin socket are aligned rearwardly of the respective electrical prong apertures and the ground pin aperture. A transversely extending shaft having a knob on its front end extends a predetermined distance within cylindrical housing so that a transversely extending groove on its bottom surface aligns with the right and left blade prong of a male electrical plug prior to its insertion. This allows the male electrical plug to be freely inserted or removed. By rotating the knob, the shaft will cause one edge of the transversely extending groove in the bottom surface of the shaft to bind against the top edge of the left blade prong and prevent its removal from the lockable electrical receptacle.
The second embodiment of the lockable electrical receptacle functions in the same manner as the first embodiment but has a plurality of laterally spaced sets of electrical prong apertures so that a plurality of male electrical plugs can be inserted therein. The shaft would pass through almost the entire width of the bottom housing member and have its respective transversely extending grooves in its bottom surface aligned with their respective left prong electrical apertures.